Pump and like device for controlling the rate of delivery of fluids



Aug. 6, 1929.. E. LUNGE PUMP AND LIKE DEVICE FOR CONTROLLING THE RATE OF DELIVERY OF FLUIDS Filed Ndv. 15 1925 5 Sheets-Sheet 1 WWW/flag:

4 ill Aug. 6, 1929. LUNGE 1,723,875

PUMP AND LIKE DEVICE FOR CONTROLLING THE RATE OF-DELIVERY OF F'LOIDS Filed Nov. 13, 1925 s sheets-sheaf 2 5" $1? m I urlnlll l "mm-mm 4| Ill lmmupill I Ill.

2:7 J V i a 4M 5% 39 $0410 441 TE 55 [I Aha- Q: p165 PUMP AND LIKE DEVICE FOR CONTROLLING THE RATE OF. DELIVERY OF FLUIDS Filed Nov. 15 1925 Shests-$heet 5 O n W Aug 5, 1929. LUNG}:

PUMP AND LIKE DEVICE FOR CONTROLLING THE RATE OF DELIVERY OF FLUIDS Filed Nov. l5, 1925 5 Sheets-Sheet 4 15 if i m zsa zsjz/ 86. I II g @1154 1 2 I]; 225* IE i u I l f5 5 43 77 I n r i Z31 J16 J55 INVI'N TOW AugQG, 1929; EWLUNGE 1,723,875 PUMP AND'LIKE DEVICE FOR CONTROLLING THE RATE OF DELIVERY OF FLUIDS Filed Nov. 13, 1925 5 Sheets-Sheet 5 Aug, 6, 192a Y en LUE'GIE, OF LONDON, ENGLAND, ASSIGNUR T0 GUURTAULIDES Lli'ldllllltlll), @W,

lhtllil'lllflll, ENGLAND, A BRITISH CUIMHPANY.

Plllilllf Mill) lLllKlE DIE-VICE FOR CONTROLLING THE RATE 0.1T DELIVERY HF FLUIDEF,

' Application filed November 13, 1925, Serial No. eat-re, and in (treat juritain November 20, rear.

This invention is for improvements in or relating to pumps and like devices for controlling the rate of delivery of'fiuids, and has for its object to provide an improved construction of the same whereby, amongst other advantages, an unvarying rate of continuous delivery can be obtained. This fea' with the spinning solution at an unvarying pressure. Owing to the nature of the materials used, it is not practicable'to obtain the desired uniform pressure by means of large reservoirs or the lilre and the presentinvention provides an apparatus which can deliver the solution to, the spinning-nozzles at an unvarying rate or pressure. It will be understood that this invention is not limited to this particular application of it; but may be used with any'liquid or fluid of which it is desired to obtain a continuous and uniform rate of delivery.

This invention comprises an apparatus for obtaining a continuous delivery of liquid at constant velocit and constant pressure, the combination with two cyclically-actuated pumps whereof each has a delivery-stroke, which includes a period of delivery. at the desired uniform rate, towards an outlet common to both of them, and whereof the said uniform delivery periods successively overlapone another, of a chamber which is expanded at such a rate as to accommodate within the apparatus during the overlapping periods and without altering the fluid pres sure in the apparatus, all the flow towards Ell the outlet that is in excess of the desired amount.

According to another feature of this'invention, apparatusas above set forth isv so constructed that the said chamber varies in volume at all times at the same rate as, but in the opposite sense to, the varying volthe nozzle should be continuously supplied umeof one of the delive y pnmps. Conveniently, the apparatus comprises two ire-- ciprocating delivery-pumps, and a third re ciprocating pump which provides the chamber aforesaid to accommodate the excess flow.

According to another feature of this in vention, the reciprocating pump which accommodates the excess flow is constituted by the rear face of the piston ofone of the delivery-pumps, and that portion of the cooperating cylinder which is termina 1- by the said face,

According to yet another feature of this invention, apparatus as above set forth is characterized in that the excess flow ofv the liquid which is being delivered towards the outlet is diverted into the accommodating chamber out of the path of flow towards the outlet, and thereby is temporarily subtracted from the total flow. -l Vhen such apparatus comprises two delivery-pumps and a third or accommodation pump, as above mentioned, it is further characterized in that all three pumps can he put in direct communication with the main outlet.

Pumping devices in accordance with this invention may talsze various forms, and the invention also comprises certain details of construction and arrangement of pumps as hereinafter described with reference to the accompanying drawings, in which- Figure l is a plan of one construction in section on the'line 1--1 of Figure 2;

till

Figure 2 is a cross-sectional view of the same on the line 2-2 of Figure 1, or Figure 4; r

Figure 3 is an elevation in section entire line 83 of Figure 2;

Figure dis a plan; 7

Figure 5 is an end view in section on the line 55 of Figure 4;

Figure 6 is a detail; i v

Figure 7 is an elevation-incross-section of a second, modified construction;

Figure 8 is an elevation in section on the line 8-8 of Figure 9, of a third construction;

Figure 9 is a longitudinal elevation in section on the line 9-9 of Figure 8;

Figure 10 is an elevation in section on the Flt ' tion;

line -10 of Figure 11, of a fourth construetion;

Figure 11 is a plan of the same construclan on the line Figure 12 is a sectional v 12.-12 of Figure 13 of a fi h construction;

Figure 13 is a-section on the line 13-13 of Figure 12,

Figure 14 1s a sectional plan on the line 1414 of Figure 15 showing a sixth construction;

Figu

Figure 16 is a diagrammatic drawing showing the arrangement of a group of pumps; and

Figure 17 is a sectional elevation showlng one form of operating means for reciprocating the pump plungersj with a through passage 19 controls communication between the cylinder 13 and the cylinder 14. The cylinder 14 is provided with an outlet passage 20 which, in the case of artificial silk spinning-apparatus, communicates with a spinning-nozzle.

Each of they cylinders aforesaid is provided with a piston 21, 22, 23, respectively,

and these pistons project from the open ends of the cylinders remote from the connecting assages 11, 15. The piston 23 is so operatecf that on its inwardor deliverystroke, it has a perfectly uniform rate of movement except at the ends of its stroke when its motion is being reversed; its return-stroke is made to take place in a lesser time and any convenient rate is used. The piston 22 is moved at exactly the same rate as the piston 23 but in the opposite sense,

that is to say, the piston 22 has an outward stroke which is perfectly uniform except at the ends, and a quicker return-stroke. The piston 21 has a cycle of movement similar to that of the piston 23, but its cycle is displaced in phase so that the period of uniform delivery during the inward movement of the piston 21 commences shortly before the corresponding period of the piston 23 stops,

and continues until the piston 23 has completed its return-stroke and has started its p re 15 is a section on the line 1515 of Figure 14;

Like reference characters indicate like next period of uniform delivery. The piston 21 then has a return-stroke which is completed before the piston 23 completes its delivery-stroke. The result is that the periods of uniform movement of the pistons 21, 23 successively overlap one another.

The valves 16, 18 are adjusted to open and close communication through the passages 11, 15 during the cycle of operations as hereinafter described.

In order to describe the operation of this device, let it-be assumed that the cylinder 14 is filled with liquid, and that the piston 23 has started to move inwards at a uniform rate. The piston 22 is near the inner end of the cylinder '13 and is moving, outwards at the same rate 5 the piston 21 has just commenced its outward stroke. The valve 1.8 is in its closed position and the valve 16 is open. The movements of the various pistons continue from this point in the manner above described. The li uid in the cylinder 14 isdelivered throug the outlet 20 at a perfectly uniform rate determined by the rate of movement of the piston 23. The cylinder 12 is filled, as the piston 21 moves outward, by liquid flowing in from the supply-pipe 10 through the passage 11 and the valve 16. Also, the cylinder 13 is filled by liquid entering in the same manner, as the piston 22 moves outward at its slow uniform rate. Whilst the slow outward movement of the piston 22 is continuing, the piston 21 reaches the outward limit of its stroke, reverses, and commences its slow uniform movement inwards, and this rate of movement is equal to that of the piston 22 outwards. The piston 21, therefore, delivers liquid from the cylinder 12 at a rate equal to the rate at which liquid flows into the cylinder 13. At this oint in the cycle, the valve 16 can be close and the.movements of the pistons 21, 22 can continue, since the volume between the faces of the two pistons remains unchanged. Immediately thereafter, the valve 18, which has been closed, can be opened, without distributing the uniform delivery of the cylinder 14 to the outlet, because the delivery which is taking place from the cylinder 12 is all accommodated within the cylinder 13.

It will be recollected that the piston 22 moves at exactly the same rate as the piston 23 but in the opposite sense. If, therefore, the piston 23 slows down so that its rate of delivery falls off from the desired uniform rate of delivery, the piston 22 will slow down by an equal amount. The piston 21, however, continues its rate of uniform delivery, and the whole of this uniform rate can no longer be accommodated in the cylinder 13. The excess rate of delivery from the cylinder 12 is equal to the reduction in the rate of accommodation provided in llll the cylinder 13, and this reduction equals the reduction in the rate of delivery from the cylinder 1d. But the liquid being de livered from the cylinder 12 can pass through the passage 19in the valve 18 into the cylinder 14 and directly to the outlet 20, so that the delivery from the cylinder 12 exactly compensates for the falling-d 1n the delivery from the cylinder 14. The piston 23 can now be stopped. The piston 22 stops at the same time, and the whole of the delivery from the cylinder 12 by the piston 21 passes to the outlet, and the desired unitorm rate of delivery. is therefore maintained. During the continuance of the unit'orm delivery of the piston 21, the piston 23 moves quickly outwards; the piston 22' similarly moves quickly inwards and, in so doing, delivers the liquid in the cylinder 18 into the cylinder 14 to fill it, the flow taking place through the passage 19 of the valve 18.

, en the cylinder It has again been filled the piston 23 reverses its movement and commences its unitorm delivery-stroke. The piston 21 is now nearing the end of its delivery-stroke, and the piston 22 is at the inner end of the cylinder 13 and commences its uniform outward stroke. The two cylinders 12, 1d are therefore both delivering to wards the outlet at the desired uniform rate but thh cylinder 13 is providing accommodation at the same desired rate for liquid from one of them. During this overlapping phase, the valve 18 can be closed so that the whole of the delivery to the outlet 20 is made by the piston 23. immediately thereafter,

the valve 16 can be opened so as to put the cylinders 12, 13 into communication with the supply-pipe 1t), and immediately thereafter, the piston 21 can stop its uniform delivery and commence its return-stroke. This is the state which. was assumed above at the commencement ot the description at the cycle ct operations and this cycle can be repeated indefinitely. a

llt will be seen that the piston 23 and the cylinder 14 constitute one delivery-pump,

. the piston 21 and the cylinder 12 constitute the other delivery-pump, and the piston 22 with the cylinder 13 constitute the accommodation chamber or pump referred to in the earlier part of this specification.

The detailed construction of this pump will now be described. The body of the device is formed as a'casting 24 of suitable shape, and the cylinders 12, 13, 14 are formed as open-ended bores of uniform diameter therein. The connecting passage 11,

- 15 is formed as a through-bore (see Figure 2) and the ends are plugged at 25, 26. These plugs may be permanent, but itis preferred to make them removable so that the whole of the interior of the pump can be easily cleaned. The supply-pipe 10 is also formed in the body of the pump, being a straight neighbouring pump-body.

bore through it from end to end, as shown liquid may be maintained through all the pumping devices for ensuring its ho1nogeneity, and also a pump may lie-rendered inoperative by causing it to deliver into the return-flow-pipe when necessary, such anarrangement being illustrated hereafter. The transverse connecting passage 11, 15 is preteraloly s0 situated that it provides communication from the bottom of the supply-pipe 10 to the bottoms of the cylinders 12, 113, 14:, as shown in Figure 2, and an auxiliary passage 28: is also used to provide com munication between the tops of the cylinders 12, 13, 14. This arrangement ensures that when the pump is being filled with liquid in the first instance, the liquid flows into the bottom of each of the cylinders and rising therein expels. the air through the. upper passage 28 to the outlet 20, so that there is no possibility of any air being entrapped in the device. The valve 18 is of course formed with two passages 19 and 29 so as to open and close the passages 15 and 28 simultaneously so that they constitute in cttect a single passage.

The body 24 ismounted on a base-platc 30 which is secured on any convenient bench 31. The pump-body is provided with a recess 32 (see left'hand side of Figure 2) to engage a lug 33 on the base 30, and the latter is furthermore provided with an upstanding flangc 34, on the right-hand side in Figure 2, which has an overhanging lip the base 30. The bolt 36 extends through the body of the pump so that when it is rotated to bring the head 3'? into engagement. with one oil the walls of the recess 38, the pump-body is forced towards the right in Figures 3 and 4, closely against a similar The contact between two neighbouring pump-bodies takes place on the ends of that portion of the body in which the supply-pipe 10 is formed, so that when a number of bodies are assern' bled together in a row, the channels 10 constitute a supply-pipe extending throughout the length of the row. Any suitable packing may be interposed, in order to ensure that the. various sections of the supply-pipe 10 may make a tight joint with one another. The. packing may be and preferably is of an elastic nature in order that a reasonable tolerance may be allowed inthe manufacture of the parts. By thus wedging the various units one against the other, and since lltll i'ected by means of rods 39,40, 41, which extend along slots in the base 30. here a plurality of the pumpsare used in a group end-to-end, these rods extend throughout the length of the group. Each rod actuates all the corresponding pistons of the group, and I'meach piston there is provided a peg 42 (see Figure 3) upstanding on the corresponding rod, so that it can engage the end of the piston and push it on its inward stroke. The various pistons are pushed outwards by the pressure of the liquid in the si1pply-pi )e entering the cylinders, or, in the case of the cylinder 14, by the pressure of the liquid transferred to it from the other cylinder 13 and it will be appreciated that such outward movement of the pistons-is controlled by the movement of the rods 39, 40,41 so that the pistons are controlled throughout the whole of the motion of the cycle of operations.

The valves 16 and 18 may be operated in any convenient manner. As illustrated in Figures 2, 3, 4 and 5, each valve projects upwardly beyond the upper surface of the body 24 of the pump, and the two are re tatably coupled, together by a link 43 pivoted on projections 44, 45 on the heads of .the valves. The valve 16 is provided with a second crank-pin 46, and a link 47 'en gaged therewith is coupled to a pin 48 up standing on a rod 49 (see Figures 3 and 4) which is reciprocated to actuate the valves. lVith this arrangement it will be seen that the two valves are operated simultaneously nstead of in succession, as described above in the operation of the. device. The only pointto be noted with regard to the design of the valves when they are operated simultaneously in this manner, is that the ports through them should be so proportioned as not to provide at any time a simultaneous opening through both valves from all three cylinders to thesupply-pipe. If it is de.- sired to operate the valves successively in the manner first above described, this could be done by means of any simple lost-motion device, or by separate, but correctly timed, operating means.

The movements of the rods 39, 40, 41 and 49 may be imparted to them by any suitable or desired mechanism. The slow uniformdelivery stroke can be made with a high de' gree of accuracy by providing a screw-feed,

as a uniform rate of rotation of a screwedspindle can be obtained within very close limits, and a screw-thread can be cut to a very high degree of. accuracy.

My co-pending application 68873 filed November 12, 1925' discloses mechanism for reciprocating the pump rods. One such mechanism is shown in Figure 17 of the accompanying drawings in which the ends of three push-rods for the pumps are shown at Three cams at 145 mounted for rotation as at 147 engage the rods 148 to operate the latter at the desired rate of speed.

The link 47 aforesaid is preferably made of a laterally yielding nature, so that it can be disengaged from the pin 48 (Figure 3) by lifting it up therefrom. This enables any individual pump or a group to be rendered inoperative without affecting the other pumps of the group, for the valves of that particular pump would remain sta' tionary. If the valves are left stationary in such a position that the valve 16 is left closed, the operation of the pump would continue until each of the pistons had been pushed to the innermost end of its stroke. They would not move outwards again, because there would be no supply-pressure to effect this movement.

When filling and starting the pumps, the formation of air-pockets or bubbles within the device is prevented if the pistons are all retained 'at the innermost ends of their re spective strokes, and this may be effected by means of the device illustrated in Figure 6. It consists of a plate 490 which is notched at 50 to fit over grooves 51 on the ends of the pistons (see Figure 4), and itis also notched as at 52 to engage with bolts 53 on the end face ofthe body 24 or" the pump. -The pistons are all pushed home and the plate 490 dropped on the bolts 53 to engage with the three pistons and hold them against longitudinal movement. The valve 16 is turned into its open position so that the liquid can flow in from the supplypipe to fill the various cylinders, or even the normal operation of the pumps can be started without disconnecting the valves, as after one complete cycle the liquid will have filled the device and normal delivery will follow thereafter.

Figure 7 illustrates a modified construction of pump. In this case, the supply-pipe is indicated at 53, and the three cylinders corresponding to 12, 13 and 14 of the construction above described are arranged as at 54, 55 and 56. A single valve-member 57 controls communication between the supply pipe and the first cylinder, and also be tween the second cylinder and the third cylinder. The connecting passages are preferably arranged in pairs, as shown at 58, 59, and the final delivery takes place from the cylinder 56 through a passage 60 This passage 60 opens into a' chamber 61 provided with a rotable valve-member 62. In one position of this valve-member, the passage 60 is open to the normal outlet 63, and if this valve-member is rotated through 180 the passage 60 is placed in communicw tion with a return-flow pipe 64 correspondtill ing to the pipe 27 of Figure 2. This bypass device is used when it is desired to stop the delivery of one of a series of pumps for any reason. A similar icy-passing device may be provided on the pump illustrated in Figures 1-5, if so desired.

The construction illustrated in Figure 7 may be operated by means similar to that illustrated in Figures l-5, in so far as the pistons for the various cylinders are concerned, and the valve 57 can be operated as were the two valves l6, 18, when coupled together.

in Figures 8 and 9, yet another construction is illustrated; In this case, the supplygipe is indicated at and the three cyliners, corresponding to 12, 13 and la aforesaid, are arranged in a vertical plane above the pipe65, at 66, 67, 68. 'lihe outlet 69 from the cylinder 68 can be put into communication with the main outlet 70;or with a return-flow-pipe 71 by means oi a by pass valve 72. A feature oi this construction is that the various pump-cylinders are constituted by annular chambers termed by two piston-members oil didering diameter. The controlling valves are indicated at 73, M respectively, The first pump-chamber 66 is constituted by the an nular space surrounding a plunger '15 which is of smaller diameter than a plger 76 which engages it endwise. Movement oil the two plungers towards the right in Figure 9 constitutes the rapid inlet or suction stroke of this pump, and the slow uniform delivery-strohetakes place in the opposite direction. The other two pumps are constructed similarly, but they are arranged to extend in opposite directions trom the connecting passage 77, that is to say, the accommodation pum has its larger plunger 78 on the left, and its smaller plunger 79 on the right, whilst the delivery-pump has its larger plunger on the right at 80' and its smaller plunger on the left at ill. The operation of this pump is exactly the same as the operation of that described in connection with Figures 1-5, and the two pumps 78, 79 and 80, 81 have exactly the same movement but they are in opposite phase. That is to say, when the plunger d0 moves towards the left on its delivery-stroke, the plunger 78 has to move on its suction-stroke. With the above-described arrangement' of the parts, this movement is also towards the left in higure 9, so that the tour plungers 78, 79, 80., 81 all move to-and-tro in exactly the same manner.

lit will be seen that by adopting this arrangement of annular pump-chambers, the parts corresponding to the pistons oil" the pumps extend endwise right through the pump-body, and when a nber of pumps are assembled together side-by-side in close proximity, the corresponding plungers can abut one another if their lengths are suitably selected. A drive can then be impartfid formed as through-bores 143, M l respective- 1y, which open into one another at the ends of the pump body. Very great simplicity is thereby attained, since any number at" units can be assembled end-to-end and a single driving device rovided only at one end of the group. it e return-stroke may be efi'ected by means of any suitable driving mechanism, a yielding hydraulic. device he ing particularly suitable in that it will hold the plungers up against the ,driving-memher which thereby edectivelyeontrols their movement in both directions,

In the construction illustrated in li igures 10 and 11,. the three pump-chambers are indicated in the same sequence as in the descriptions of the previous constructions, at 82, 83, 8d, the supply-pipe being shown at 85, and the return-filow-pipe at .86. A. single valve-memberfi'l is sed to control the communication between t e supply-pipe and. the cylinders, this valve being rotatable into two positions it chamber 88 in the valve is provided with downward and upward. entensions 89, respectively.- in one setting oi the valve, the cavity 89 provides com-' munication from the supply-pipe 85 to the first and second cylinders 82, 83 the third cylinder 8% being then open only to the out let 91, whilst in the other setting oi the valve, the supply-pipe 85 is shut oh and the c linders 82, 83 are in communication tirou h the cavity 90 with the cylinder 8t and t e outlet. 'llhe operation oil this device for controlling the rate of delivery oil the fluid is exactly the same as with the construction illustrated in Figures l-5, and various other-details oi construction can be similar to an oi the constructions already described. us, the pumps could be con-- stituted by plungers working in open-ended bores, or by coaxial plungers oi different diameter, but such details need not be re peated.

The construction illustrated in Figures 12 and 13 is-similar to the constructions previously described in its mode of operation, but it differs in that only two cylinders are used, and a piston in one of them constitutes by one of its laces the piston at bill Mill

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lilt/ the delivery-pump, and by the other of its moved by means of plungers 99, which extend endwise from the end of the body to co-operate with corresponding plungers of another similar device in the manner above described. The plunger 99 is of less diameter than the plug 98,'so as to provide an annular pump-chamber around it. 'As illus-' trated, the plunger 100 is'similarly made-0f smaller diameter than the plug 98, but this is not essential, as the annular space around the plunger 100 is opened to atmosphere and is not used as a pumping-chamber. The plungers are a good fit in bushes such as 101 which are screwed or otherwise secured in thebody of the casing, this construction being necessitated by the fact that the plug 98 is of larger diameter than the plunger 99.

The pumping chamber 97 is open at all times by a passage 102 to a valve-chamber 103, this chamber being provided with a valve 104 which can open or 'close communication therefrom to a passage 105. The chamber 103 also communicates at its other end with a assage 106, but this passage is never close The passages 105', 106 communicate respectively with the two ends of a cylindrical bore 107 in which there slides a close-fitting plug 108 similar to the plug 98. The-plug'is actuated by 'lungers 109, 110 each of smaller diameter t an the plu so that two annular chambers are provide one at each end of the chamber 107. The plug 108 constitutes by its face 111 the piston of a delivery-pump, and by its other face 112 the piston of the accommodation pump. The main outlet fromthe deliverypump is indicated at 113, being opposite the passage105' aforesaid which is controlled y the valve 104.

The operation of this device in so far as it comprises two delivery-pumps and an ac commodating pump, is similar to that of the construction illustrated in Figures 1 5.

' With the parts-in the position shown in Figure 12, the piston or plug 98 has started its,

uniform delivery, moving towards the left. The liquid is being delivered through the passage 102, chamber 103, passage 105 (which the valve 104 has opened) to the outlet 113. The plug or piston 108 is about to start its quick return movement towards the left, and in so doing the liquid in the accommodation chamber 107 is transferred through the passage 106, chamber 103, passage 105, to the other side of the piston 108', and this charging of the delivery-pump on the right-hand side of the piston 108, is completed before the piston 98 completes its uniform delivery-stroke. The piston 108 then commences its stroke of uniform delivery rate towards the right, and thereby delivers liquid .to the outlet 113, and the piston 98, which is nearing the end of its uniform delivery period, delivers its liquid into the accommodation space to the left of the piston 108. The valve 104 is then closed and the valve 95 is opened. The piston 98 then starts its quick return-stroke and draws in a fresh charge of liquid from the supplypipe through the passage 96 and liquid also flows during this period through the passage 102 and chamber 103 into the accommodation chamber on the left of the piston 108. The piston 98, having reached the end of its stroke towards the right in Figure 12, reverses its motion and commences its rate of uniform delivery and the valves are then readjusted to the positions shown in Figure 12, and soon thereafter the piston 108 reaches the end of its delivery-stroke, that is to say, the parts have all returned to the positions illustrated and the cycle of operations has been completed and is ready for starting a new cycle.

In the construction illustrated in Figures 14 and 15, the apparatus comprises a body 114 provided with a number of longitudinal borings through it. Of these the supply-pipe is constituted by the boring 115,

.and the return-flow-pipe by 116. The three pump-chambers are shown at 117, 118 and 119 respectively, and there are also provided two other bores 120 and 121 to receive sliding cylindrical valves. Transverse passages 122, 123 and 124 provide communication from the inletipe to the various vvalve spaces and cylin ers, and the outlet from the pump is indicated at 126, this outlet communicating alternatively with a spinning-nozzle on 127 or with the return-flowpipe 116 by means of a suitable by-pass valve 128.

In this case all the pistons are of the differential type, as shown in Figure 14, but the two parts are preferably separated and held apart by the internal pressure of the liquid which is being delivered, so as to avoid any interference with the free flow of the liquid and in particular to avoid any undesirable eifects of surface tension at the junction between the narrower and wider piston sections. As shown in Figure 14, the cylinder 117 has a larger piston 129 and a smaller piston 130. The corresponding parts of the cylinder 118 are shown at 131, 132 respectively.

The pairs of pistons 129, 130 and 131, 132 are moved simultaneously in the same direction, that is to say, alternately towards the right and towards the left in Figure 14, by means of. a rod underneath the pump-body carrying a member 133 which engages each pair of pistons. The piston 134, which is in the cylinder first entered by the liquid from the supply-pipe 115, is moved in the manner above described oppositely to the piston 131 by a suitable push-rod135. The two valves, of which one is shown at 136, in Figure 1a, may-be operated in any convenient manner, preferably by arranging that the valves of different units abut one another lengthwise and are all moved simultaneously by a suitable device at the end of the row.

The various passages are closed where necessary by plugs 137 which are shown as of,

tapering formation with a yielding packing 138; these plugs are held in place by a suitable loracket 139 on the bench against which the pump body is pressed. This form of plug is illustrated as a modification which can ,be applied to any of the constructions of pump hereinbefore described. 7

The operation of this particular construction need not be described in detail, as it is exactly similar to the various constructions hereinbefore described, it being understood that the liquid passes from the supply-pipe 115 through the valve-chamber 120 into the first pump-cylinder 119; the liquid is delivered from this chamber 119 either directly to the outlet by the passages 123, 12 1, or in another phase of the cycle is delivered into the chamber 118 and is delivered thence to the chamber 117, from which it is subse-. quently delivered to the outlet.

Any desired means, such as that shown in Figure 17, maybe used for imparting the v requisite movement to the pump plunger.

A number of different embodiments of this inventlon have been described, 111 order to show the great flexibility ofdesign which is possible with devices in accordance with this invention. The operation of all of them is similar, in so far as the two pumps deliver the liquid successively to the outlet, and during the overlapping periods of their delivery, the liquid from one 01 the pumps is diverted from its normal-path of flow from the pump'towards the finale outlet, into a chamber which expands at a rate exactly equal to the rate of delivery of liquid in ex cess of the desired rate. It will also be appreciated that in order to prevent any irregularities in the rate of delivery arising from the operation of the valves controlling the various passages, these valves should be of a type which in its opening and closing movements does not alter the cubic content of the pump charge. Apart from this limitation, any desired construction or arrangement of valves may be used, Whilst a number of constructions have been described, it is to be understood that the invention is not limited to them, or to any other specific construction, for it will be obvious that many other modifications and arrangements of device may be used in accordance with this invention for providing a continuous and uniform delivery of fluids.

What I' claim as my invention and desire to secure by Letters Patent is '1. In apparatus for obtaining a continuous delivery of liquid at constant velocity and constant rcssure, the combination of two reciprocating pumps, a delivery outlet common to both of them, means for operating said pumps so that each has a deliverystroke, which includes a period of delivery at the desired uniform rate towards said outlet, and the said uni-form delivery periods successively overlap one another, a chamber, means for varying the volume thereof at the same rate as, but in the opposite sense to, the varying volume of one or the delivery pumps, and means roviding communication etween said cham er and said pumps.

2. in pumping apparatus, the combination of two reciprocating delivery pumps, means for operating them so that each has a delivery stroke which includes a period of uniform delivery that overlaps at both ends the period of unitorm delivery of the other, a third reciprocating pump which moves oppositely to one of said pumps, and means providing communication between each or said, first pumps and said third pump.

3. ln pumping apparatus, the combination of a double-ended reciprocating pump, a single-ended reciprocating pump, means for operating said pumps so that each has a de livery stroke whichcomprises a period of uniform delivery, which period overlaps the similar period of the other pump, and means providing communication from both of said pumps toan outlet common .to both of: them.

4. In pumping apparatus, the combination of two reciprocating pumps which deliver alternately without cessation to an outlet common to both of them, and a chamber of variable volume which accommodates all that portion of the total delivery in excess of a predetermined quantity. 1

5. In pumping apparatus, the combination of a pump-cylinder, a plunger therein, means for reciprocating said plunger in such manner that it moves with a uniform velocity during a portion of its delivery stroke, and pauses after each stroke, a second pumpcylinder, a plunger therein, means for reciprocating said plun' er in such manner that it moves with a uni orm velocity during a and said chamber, valve-means controlling said communicating means, valve-operating 'means adpisting said valves during the pauses aforesaid which occur between the working strokes of the pump, and means providing communication from each of said pump cylinders to said delivery-pipe.

6. In pumping apparatus, the combination 10 of two reciprocating pumps operated at such a rate that they have successively overlapping periods of uniform delivery, a chamber which is supplied from one of said pumps, and delivers to the other of said pumps, and means for varying the volume of said chamber in such manner that it accommodates at all times any flow of liquid in excess of the maximum delivery of one pump. In testimony whereof I aflix my signature.

ERNEST LUNGE. 

